The UAF42 is a universal active filter that can be
configured for a wide range of low-pass, high-pass,
and band-pass filters. It uses a classic state-variable
analog architecture with an inverting amplifier and two
integrators. The integrators include on-chip 1000pF
capacitors trimmed to 0.5%. This architecture solves
one of the most difficult problems of active filter
design — obtaining tight tolerance, low-loss capacitors.
A DOS-compatible filter design program allows easy
implementation of many filter types, such as
Butterworth, Bessel, and Chebyshev. A fourth,
uncommitted FET-input op amp (identical to the other
three) can be used to form additional stages, or for
special filters such as band-reject and Inverse
Chebyshev.
The classical topology of the UAF42 forms a
time-continuous filter, free from the anomalies and
switching noise associated with switched-capacitor
filter types.
The UAF42 is available in 14-pin plastic DIP and
SOIC-16 surface-mount packages, specified for the
– 25 ° C to +85 ° C temperature range.